River braided

Conceptual diagram of a braided river and its stratigraphic deposits. Zones of thread confluence and thread splitting, shown by blue arrows, facilitate the formation, accretion, and deformation of bank-attached and mid-channel bars. Within a larger channel-belt sand body, bar deposits can be stratigraphically preserved as packages characterized by sigmoidal bar clinothems that accrete in the direction of bar growth and downlap (e.g., blue arrows in cross-stream stratigraphic view) onto older deposits

Comments

Regional Geography, Systematic Geography, Idiographic, Nomothetic, Inductive and Deductive Approaches

T wo major ways of studying Geography : the Regional Approach and the Systematic Approach . It also explains the related ideas of idiographic vs. nomothetic and inductive vs. deductive reasoning , especially in the context of the Hartshorne–Schaefer debate . 1. Regional Geography: “All About One” Regional Geography studies one particular region in detail . A region is an area that has some degree of homogeneity (sameness) within its boundary but is also unique or different from other regions . For example, if we study Palakkad District , we may study: Relief and drainage Climate Soil Vegetation Agriculture Population Occupation Economy Culture Political characteristics The purpose is to understand the complete geographical personality of Palakkad and the relationships among its different features. Key concepts Region: A geographical area with identifiable characteristics and boundaries. Homogeneity: Si...

Multispectral and Hyperspectral Imaging Systems

The main idea is how a remote-sensing sensor collects information about an area . A sensor does not simply take an ordinary photograph. It measures the electromagnetic energy reflected or emitted by objects in different wavelength bands . Depending on how many bands are measured and how the sensor collects them, different imaging systems are used. 1. Multispectral vs. Hyperspectral Multispectral imaging (MSI) records information in a limited number of relatively broad, separate spectral bands , such as blue, green, red, near-infrared and shortwave infrared. Hyperspectral imaging (HSI) records information in many narrow and usually contiguous spectral bands . Therefore, it provides a much more detailed spectral signature of each pixel. The resulting dataset is commonly called a hyperspectral data cube (hypercube) because it contains: X-axis → spatial information Y-axis → spatial information Z-axis → wavelength/spectral information Thus, hype...

Discrete Detectors and Scanning mirrors Across the track scanner Whisk broom scanner.

Multispectral Imaging Using Discrete Detectors and Scanning Mirrors (Across-Track Scanner or Whisk Broom Scanner) Multispectral Imaging: This technique involves capturing images of the Earth's surface using multiple sensors that are sensitive to different wavelengths of electromagnetic radiation. This allows for the identification of various features and materials based on their spectral signatures. Discrete Detectors: These are individual sensors that are arranged in a linear or array configuration. Each detector is responsible for measuring the radiation within a specific wavelength band. Scanning Mirrors: These are optical components that are used to deflect the incoming radiation onto the discrete detectors. By moving the mirrors, the sensor can scan across the scene, capturing data from different points. Across-Track Scanner or Whisk Broom Scanner: This refers to the scanning mechanism where the mirror moves perpendicular to the direction of flight. This allows for t...

Thermal Infrared Remote Sensing

1. Principles Thermal Infrared Remote Sensing is based on the detection of naturally emitted electromagnetic radiation from objects, rather than reflected solar energy. According to Planck's Radiation Law , all objects with a temperature above absolute zero (0 K) emit electromagnetic radiation. For Earth surface features, the peak emission lies in the Thermal Infrared (TIR) region of 3–14 μm of the electromagnetic spectrum. The amount of radiation emitted is primarily a function of surface temperature and emissivity . Sensors measure the radiant energy flux density (W/m²) , which is later converted to surface temperature using Stefan-Boltzmann's Law . 2. Radiation Properties in TIR Emissivity (ε): Ratio of radiation emitted by a surface to that emitted by a perfect blackbody at the same temperature. Natural surfaces like water (ε ≈ 0.98) have high emissivity, while bare soils and metals have lower values. Blackbody: An idealized object th...

Satalite

Landsat → Land resources SPOT → High-resolution mapping IRS → Indian natural-resource mapping ASTER → Geology + thermal + DEM QuickBird → Very high spatial resolution MODIS → Daily global monitoring GOES → Weather monitoring AVHRR → Weather + vegetation + ocean AVIRIS → Hyperspectral imaging Highest spectral resolution: AVIRIS (224 narrow bands) Highest spatial resolution in this list: QuickBird (~0.61 m PAN) Highest temporal frequency: GOES (minutes) Best broad global monitoring: MODIS Indian sensors: IRS-LISS III and LISS IV Hyperspectral: AVIRIS Thermal + multispectral + DEM: ASTER abbreviations MSS – Multispectral Scanner System TM – Thematic Mapper ETM+ – Enhanced Thematic Mapper Plus GOES – Geostationary Operational Environmental Satellite AVHRR – Advanced Very High Resolution Radiometer HRV – High Resolution Visible HRVIR – High Resolution Visible and Infrared HRG – High Resolution Geometric ...

Vineesh V, Geography

Search This Blog